1. Field of the Invention
Embodiments of the present disclosure generally relate to power conversion, and more specifically, to detecting AC grid voltage anomalies during power conversion.
2. Description of the Related Art
Solar panels have historically been deployed in mostly remote applications, such as remote cabins in the wilderness or satellites, where commercial power was not available. Due to the high cost of installation, solar panels were not an economical choice for generating power unless no other power options were available. However, the worldwide growth of energy demand is leading to a durable increase in energy cost. In addition, it is now well established that the fossil energy reserves currently being used to generate electricity are rapidly being depleted. These growing impediments to conventional commercial power generation make solar panels a more attractive option to pursue.
Solar panels, or photovoltaic (PV) modules, convert energy from sunlight received into direct current (DC). The PV modules cannot store the electrical energy they produce, so the energy must either be dispersed to an energy storage system, such as a battery or pumped hydroelectricity storage, or dispersed by a load. One option to use the energy produced is to employ one or more inverters to convert the DC current into an alternating current (AC) and inject the AC current onto the commercial power grid. The power produced by such a distributed generation (DG) system can then be sold to the commercial power company.
When coupling generated AC current to the commercial power grid, the AC current must be coupled such that it is in-phase with the AC commercial grid voltage. In order to achieve this, grid-connected DG systems receive a reference signal, i.e., a reference of the AC grid voltage, from the commercial power grid and phase-lock to the grid reference signal. As such, zero-crossings of the AC grid voltage are utilized to ensure that the injected AC current and the AC grid voltage are phase-aligned. However, in some instances, the AC grid voltage may experience irregular zero-crossings, causing the DG system to improperly inject the generated AC current onto the commercial power grid and resulting in damage to the DG system.
Therefore, there is a need in the art for a method and apparatus for identifying anomalous AC grid voltage zero-crossings and operating a grid-connected DG system accordingly.